Foamable resole resin composition

ABSTRACT

This invention relates to an improved foamable resole resin composition comprising a resole resin, a blowing agent and a surfactant wherein said improvement comprises incorporation dispersed calcium oxide particles in said composition providing a foamable resole composition curable to a non-corrosive foam. Methods for preparing, foaming and curing said noncorrosive foams are disclosed.

This is a continuation, of application Ser. No. 912,815, filed June 5,1978, now abandoned.

BACKGROUND OF THE INVENTION

Foamable phenolic resole resin compositions are known comprising aresole resin, a blowing agent and a surfactant. U.S. Pat. No. 3,389,094discloses such systems. Such compositions have been optimized by theselection of the blowing agents and surfactants to improve foamabilityand the structure of the foams.

Such compositions are based on incompletely condensed phenolic resoleresins of phenol and formaldehyde. When such compositions are mixed withan acid catalyst and a blowing agent, an exothermic reaction withfurther condensation causes liberation of gas by the blowing agent. Thecuring resin has an increased viscosity which prevents the escape ofsaid gases and the composition expands to a foam with a substantiallyclosed cell structure. Finally, the resin cures completely to a rigidfoam of great utility for insulation uses. The cured phenol/aldehyderesole resins have fire and smoke retardant properties which can beincreased further with certain additives giving added utility.

Acids are used to foam and cure such foams, hence, leave the cured foamwith a pH below about 3 which is corrosive to metal building materialswhen the foams are used as building insulation. It is the objective ofthe present invention to provide foamable resole resin compositions thatare curable to noncorrosive foams.

SUMMARY OF THE INVENTION

The invention relates to an improved foamable resole resin compositioncurable to a non-corrosive foam, comprising a resole resin, a blowingagent and a surfactant, wherein the improvement comprises, havingpresent in said composition dispersed calcium oxide particles largerthan 60 mesh.

The invention also relates to an improved process for preparing afoamable resole resin composition, curable to a non-corrosive foam,comprising blending a resole resin, a blowing agent and a surfactantwherein the improvement comprises dispersing in said composition calciumoxide particles having a particle size larger than 60 mesh.

The invention also relates to an improved process for foaming foamableresole resin composition, the improvement comprising: adding an acidcatalyst to the composition and allowing said composition to foamforming a cellular material.

EMBODIMENTS OF THE INVENTION The Resole Resin Solution

Any conventional water soluble resole resin can be used. During thenormal manufacture of single stage resole-type liquid phenolic resins abasic catalyst is utilized. To stabilize the finished resin, the base isusually neutralized at the end of the manufacturing process. Theneutralization results in the formation of either a soluble or insolublesalt depending on the base catalyst and neutralizing acid employed.Since the presence of excess salt can be deleterious to certain end useproperties, it is often removed from the resin by techniques such asinsoluble salt filtration or ion exchange. From both a cost and polutioncriteria, it is desirable to avoid removing the salt from the resin. Theaqueous resole resin solutions preferably are those that have beenneutralized so as to provide particular inert salts that do not need tobe removed but enhance the properties of the aqueous resole resinsolutions.

The resole resins are formed using bases containing polyvalent cationssuch as calcium and barium. The cation is converted to a highlyinsoluble oxalate salt at the end of the manufacturing process. Thecation so inerted does not interfere with key application properties ofthe resole resin.

The calcium or barium oxalate is formed in situ in the resin as veryfine insoluble particles which results in very stable dispersions withno tendency to settle or coagulate. The highly insoluble nature of thesesalts make them, in principle, a highly inert dispersed filler withlittle tendency to adversely affect key properties, e.g. moistureresistance. Because the dispersions are colloidal, in nature, the resinscan be pumped, sprayed and generally handled like salt free resins.

Aqueous resole resin solutions containing dispersed oxalate salts arebasically resole resins prepared using calcium or barium hydroxide andneutralized with oxalic acid or ammonium oxalate.

The base catalyzed reaction of from 1.3 to 2.8 mols of formaldehyde withone mol of phenol is carried out in the presence of calcium or bariumhydroxide. Additional bases such as sodium hydroxide or organic aminesmay be added as cocatalysts and pH regulators for the resin system.Typically, between 0.02 and 0.30 mol equivalents of total base per molof original phenol are utilized. The reaction is carried out at atemperature range of from 40° to 80° C.

The resole reaction is preferably carried out with aqueous formalinsolution of between 30-70% formaldehyde with completed reaction solidsadjusted to 60-99% by vacuum stripping to remove water or by addition ofwater.

Aqueous resoles containing dispersed salts can be used in the presenceof variety of formaldehyde scavengers and resole co-reactants. Suitableformaldehyde scavengers and resole co-reactants include nitrogencontaining organic compounds soluble in the resole, or molecular weightless than 300, containing at least one NH group per molecule reactivewith formaldehyde. Examples include ammonia, primary and secondaryamines, urea, substituted ureas, primary amides, dicyandiamide,guanidines and aminotriazines such as melamine, guanamine andbenzoguanamine. Depending on the advancement of the resole it may bepreferable to add the scavengers and resole co-reactants just prior toend use to avoid storage stability problems such as rapid loss of resolewater tolerance or the precipitation of resin components. Alternatively,the formaldehyde scavenging reaction is carried out at the end of theresole reaction, prior to neutralization with oxalate, preferably at atemperature in the range of 20° to 60° C., to minimize oligomerizationof the resole. The amount of co-reactant added can vary within very widelimits up to 1.0 mol per mol of phenol in the original reaction mixture.It is preferred to use between 0.5 and 1.5 mol equivalents of scavengerper mol of free formaldehyde present at the end of the resole reaction.

The preferred catalyst for resole stage is barium or calcium hydroxide.Supplementary bases which can be used with the main catalyst includealkali metal hydroxides such as lithium hydroxide, sodium hydroxide andpotassium hydroxide, alkali metal carbonates such as sodium carbonateand potassium carbonate, aqueous ammonia and amines of molecular weightless than 300. The process can be carried out wherein said catalystcomprises said alkaline earth hydroxides used in combination with acompound selected from the group consisting of lithium hydroxide, sodiumhydroxide, potassium hydroxide, sodium carbonate, potassium carbonate,organic amines, aqueous ammonia and mixtures thereof wherein about 0.02to 0.30 mol equivalents of combined catalyst are used per mol of phenolcharged, said alkaline earth catalysts constituting about 50 to 95% ofthe mol equivalents provided by said combined catalyst.

At the end of the reaction the barium and calcium hydroxide areneutralized with sufficient oxalate to yield a highly insolubledispersed salt and adjust the pH within the range of 3.0 to 8.5. Thesupplementary bases are partially neutralized as necessary and functionto control the resin pH between 3 and 8.5. Preferably, the pH isadjusted between 6.0 and 8.0.

The formation of the insoluble oxalate can conveniently be done byadding solid oxalic acid (usually oxalic acid dihydrate) ammoniumoxalate or water solutions of these to the resole system. Factors suchas agitation and temperature are important in obtaining a fine particledispersion. Neutralization is carried out in the range of 25° to 75° C.,preferably 30°-60° C., wherein precipitation of the inert salts occur.Generally, the higher the temperature the finer the precipitatedparticle. Agitation should be consistent with the mixing required for agiven vessel and known engineering practices for stirred tanks.Generally, the higher the agitation the smaller the particle size andcan be adjusted to an intensity consistent with the particle sizerequired by simple experimentation for a specific stirred tank.

The oxalate salt formed in water dispersion are characterized byexcellent stability with regard to sedimentation and shear. Particlesize is extremely small being below 2μ and normally averaging from about0.01 to 1.0μ, preferably 0.02 to 0.8μ.

The inert salts unexpectedly do not flocculate or precipitate and arestable in water solutions of the resole resins of this invention if theresole resin content is from about 40 to 98% by weight. If the solutionsare diluted to lower than about 40% solids then flocculation andprecipitation of the salts can occur. Hence, although the resole resinsas resins are highly dilutable, and have a water tolerance greater than500% the aqueous resole solutions containing the inert salts are notsince the inert salts will flocculate in solutions containing less thanabout 40% by weight of resole resins solids. The resole resin solutionshaving dispersed inert salts can be made dilutable by the addition of ananionic dispersing agent to inhibit the flocculation of the salts.

The preparation of the resole resin solutions preferably used in thepresent composition have been disclosed in U.S. Pat. No. 4,011,186.

The resole resins then are solutions having varying amounts of waterwith a resin solids content of 60 to 99%. However, in foamablecompositions, the preferred resole resin solutions have water contentsof less than 10%. A water-content of more than 10% in the resin isdetrimental in that it absorbs too much exothermic heat in the acidcatalyzed blowing step and thus less expansion takes place wherebyundesirably high apparent density products of non-uniform texture andlarge voids are obtained. When cellular structures of very low apparentdensity (0.2 ro 2.0 pounds per cubic foot) are to be made, awater-content less than 5% in the "A" stage reaction product ispreferred.

The resoles may have a viscosity of from about 100 to 200,000 centipoisepreferably 200 to 4000 cps. If the viscosity is too low, there is atendency for the foaming agents to volatilize in the form of largebubbles. Foams thus produced are characterized by an open cellularstructure and large voids which are not desired in foams used forinsulating purposes. The viscosity range required for the particularfoaming agent used can be determined by one skilled in the art. The sizeof the cells in the above-described foaming materials is determined by anumber of other factors: the size of the cells depends for one thing onthe nature and quantity of the blowing agent used, the reactiontemperature, and the hardening characteristics of the resin. Thus, bychanging the type and quantity of the foaming or interlacing agent, thetemperature employed and the composition of the resin, it is possible toproduce foams of different density, hardness and rigidity, i.e., foamshaving pores of different sizes.

The resoles preferably used in the present composition are the reactionproduct of a phenol and an aldehyde. Generally, from about 1.3 to 2.8mols of aldehyde per mol of phenol are employed. The lowest densityfoamed structures (0.2 pound per cubic foot) have been obtained whencondensation products were used based on 1.3 to 1.6 mols of formaldehydereacted per mol of phenol. Phenolic condensation products in which morethan 1.6 mols and up to 3 molds of formaldehyde have been reacted withthe phenol tend to release loosely bound formaldehyde during theacid-catalyzed reaction. Since this release of formaldehyde is anendothermic type of reaction, it correspondingly reduced the amount ofexothermic heat of reaction caused by the acid catalyst. Therefore,there is less heat available for vaporizing the volatile matter in thereaction mixture whereby a lower degree of expansion occurs resultinginc ellular structures of higher apparent densities, e.g., 2 to 20pounds per cubic foot. On the other hand, "A" stage condensationproducts having a reacted formaldehyde ratio between 1.0 and 1.2 molsper mol of phenol tend to harden before maximum expansion can occur andhave less exothermic heat; this is reflected by a somewhat higherdensity of the foamed structures made therefrom.

Typical of the phenols that are useful in producing suitable resoleresins are those represented by the formula ##STR1## wherein at leasttwo groups represented by R' are hydrogen atoms and the groupsrepresented by R and any remaining group represented by R' are hydrogenatoms or groups which do not impede the condensation of the phenol withan aldehyde (e.g. a substituent such as halogen atom or a hydroxy, alkylor aryl group). Illustrative of suitable phenols are phenol, cresols(particularly m-cresol), xylenols (particularly 3,5-xylenol) anddihydroxybenzenes (particularly resorcinol). Typical of the aldehydesthat can be useful in producing suitable resole resins are formaldehyde(including the oligomers and polymers of formaldehyde such as trioxane),furfural, sugars and cellulose hydrolyzates. Such aldehydes can beemployed without dilution or dissolved in suitable solvents includingaqueous alcohols (e.g. aqueous methanol, n-propanol, isobutanol orn-butanol).

FOAM PREPARATION

The manufacture of the foams is generally performed by thoroughly mixinga phenolic resole resin with a surface active substance, a blowing agentand calcium oxide particles to form said foamable resole resincomposition. When uniformly mixed an acid curing agent is uniformlymixed with said composition and the composition allowed to foam and cureusing the reaction exotherm or applied heat. The temperature of thereaction is generally kept under 100° C., if a closed cell foam isdesired. Higher temperatures can be used to form open-celled foams.

The foaming of the phenolic resin is performed after the individualcomponents have been mixed together, the blowing agent being transformedto the gaseous state. Depending on the composition of the mixture to befoamed, the foaming takes place at temperatures between 0° and 100° C.,preferably at 15° to 70° C. The resin can be foamed either in open or inclosed molds to produce bodies of a shape corresponding to the shape ofthe open or closed mold selected.

It is also possible to perform the foaming process continuously in adouble band press. In this case the components are proportioned andmixed by means of a known automatic proportioning and mixing apparatusand the mixture is fed continuously to the bands of a double band pressby means of a charging device moving crosswise to the direction ofmovement. Then the mixture is passed through a gap of selectablethickness formed between one roll and a support which may, if desired,also be a roll. The rolls can be preheated if desired. By this processboards of selectable thickness are obtained.

The hardening is generally so controlled that, as soon as the desiredfoam volume is reached, the foam structure has solidified to such anextent as to forestall collapse.

SURFACTANTS

Improvements in foam cell uniformity and size are secured by the use ofa surface active agent. Particularly useful are the non-ionic types suchas polyethers and polyalcohols, such as condensation products ofalkylene oxides (such as ethylene oxide and propylene oxide) with alkylphenols, fatty acids, alkyl silanes and silicones and like materials, asis exemplified by such products as octadecyl phenol-ethylene oxide,decyl phenol-ethylene oxide sulfate and low polymers of such materialsas polyoxyethylene dodecyl phenol, octyl phenol polyethylene glycolether, ricinoleic acid polyethylene glycolate, stearic acidpolyoxyethylene, glycolates and similar polyoxyethylates fatty acids andvegetable oils as well as polyoxyethylated fatty acid esters aspolyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitantristearate, polyoxypropylene sorbitan monolaurate,polyoxy(propylene-ethylene) sorbitan monolaurate and polyoxyethylenesorbitan pentaoleate; polyoxyethylene sorbitan monopalmitate andsiloxane-oxyalkylene block copolymers such as those containing a Si-O-Clinkage between the siloxane and oxyalkylene moieties and thosecontaining a Si-C linkage between the siloxane and oxyalkylene moieties.Typical siloxane-oxyalkylene block copolymers contain a siloxane moietycomposed of recurring dimethylsiloxy groups end-blocked withmonomethylsiloxy and/or trimethylsiloxy groups and an oxyalkylene moietycomposed of recurring oxyethylene and/or oxypropylene groups end-blockedwith alkoxy groups. Similarly useful are the quaternary ammoniumcompounds with at least 2 alkyl groups attached to the nitrogen atomlike cetyl dimethyl benzyl ammonium chloride, octadecyl dimethyl benzylammonium chloride, octadecanol-9-dimethyl ethyl ammonium bromide anddiisobutylphenoxyethoxy ethyl dimethyl benzyl ammonium chloride andsorbitan fatty acid esters such as sorbitan monlaurate, sorbitanmonopalmitate sorbitan monostearate, sorbitan trioleate and like esters.

When present, these surface active agents can be employed in any desiredamount depending on what results are desired. They serve to aid thegeneration of smaller and more uniform cells. Best results seem to besecured in using amounts from 0.3 to about 5% by weight of the agentbased on the weight of resole resin with preferred results at betweenabout 0.5 to 3% by weight. Certain surfactants may cause collapse of thefoam if employed in too great a concentration and optimum concentrationmay vary with the individual surfactant selected.

BLOWING AGENTS

The foaming agents which may be used to foam the resins of thisinvention include carbon dioxide liberating materials, low boilingaliphatic hydrocarbons, polyhalogenated saturated fluorocarbons andethers. Exemplary of carbon dioxide, liberating compounds are alkali andalkaline earth carbonates such as sodium bicarbonate or calciumcarbonate which, in the presence of an acid, liberate carbon dioxide.Another group of blowing agents comprises low-boiling organic compounds,such as carbontetrachloride, ethylene dichloride, n-butyl ether,methylal, n-pentane, chlorofluoromethane or the like. These lattermaterials are vaporized by the heat evolved in the condensation of theresin or by additionally supplied heat, thereby bringing about foamingof the liquid phenolic resin. Simultaneously with the foaming process,the hardener present in the mixture produces an increasingsolidification and finally a hardening of the foam.

Fluorocarbon foaming agents which may be used includedichlorodifluoromethane, 1,2-dichloro-1,1,2,2-tetrafluoroethane,1,1,1-trichloro-2,2,2-trifluoroethane, 1,2-difluoroethane andtrichlorofluoromethane. The compounds should have boiling points rangingfrom about -30° to 125° C. The blowing agents are employed in an amountsufficient to give the resultant foam the desired bulk density which isgenerally between 0.5 to 10 and preferably between 1 and 5 pounds percubic foot. The blowing agent generally comprises from 1 to 30, andpreferably comprises from 5 to 20, weight percent of the composition.When the blowing agent has a boiling point at or below ambient, it ismaintained under pressure until mixed with the other components.Alternatively, it can be maintained at subambient temperature untilmixed with the other components.

ACID CATALYSTS

As hardeners both liquid and pulverulent substances may be utilized. Thequantity required partially depends on the foaming agent used. If thefoaming agent consists of a solid salt which evolves gases, part of theacid is used to release the gases. If low-boiling solvents are employedas foaming agents, the proportion of hardener is lower in accordancetherewith. In addition to mineral acids such as HCl, H₂ SO₄ and thelike, water-soluble sulfonic acids are particularly well suited aswater-soluble acids, i.e., those sulfonic acids where the sulfonic acidgroup is directly linked to an aromatic ring which may be substituted.Examples thereof include benzene sulfonic acid, p-toluene sulfonic acid,phenol sulfonic acid, cresol sulfonic acid and the like. The aqueoussolutions of these acids are mainly utilized as 40 to 70% by weightsolutions. Some acids, such as p-toluene sulfonic acid, may also be usedin the pulverulent foam as hardener. The quantity of the hardener usedvaries between about 1 and 15% by weight, calculated as 100% acid, basedon phenol-resole resin.

The preferred sulfonic acid is a mixture of equal parts by weight oftoluene sulfonic acid and xylene sulfonic acid, as described in Mausneret. al. U.S. Pat. No. 3,458,449. Another foaming catalyst which has beenfound to give excellent results are novolac sulfonic acids, described inBritish Pat. No. 1,283,113.

The catalyst is generally present in the minimum amount that will givethe desired cream times of 10 to 50 seconds and firm times of 40 to 500seconds to the reacting mixture. The catalyst, however, generallycomprises foam 0.5 to 20, and preferably comprises from 1.0 to 15 weightpercent based on the weight of the resole resin.

The following examples will further illustrate the present invention,however, it is to be understood that the scope of the invention is notlimited by the examples.

Calcium Oxide Particles

Corrosion resistance for the foamable composition and the cured foam isgained by dispersing calcium oxide in the foamable resole composition.The calcium oxide (CaO) is ground quicklime formed commercially byheating calcium carbonate (CaCO₃). The particle size of the calciumoxide have been found to be most effective if they have a particle sizepassing through a 40 mesh screen and being retained on a 60 mesh screen.Larger particles may be used, however, larger particles detract from theappearance and physical properties of the foam. Smaller particles than60 mesh have been found to be too active with the curing acid catalystsso that the compositions fail to foam or collapse because they fail tocure in the foamed condition. The screen mesh or sieve sizes disclosedrefer to U.S. Sieve Series of the U.S. Bureau of Standards.

The calcium oxide can be dispersed in the resole composition byconventional means such as stirred tanks or mixers, continuous ribbonblenders or mixers wherein the mixing agitation is sufficient todisperse the calcium oxide uniformly in the resole composition inamounts of 4 to 15% by weight, preferable 4 to 10% based on the resolecomposition.

Phenolic foams are prepared by adding a strong acid catalyst to a resoleresin composition generally having 1 to 20% by weight of a blowing agentand 0.3 to 5% by weight of a surfactant all based on said resole resincomposition. Said acid catalyst is present in an amount of 0.5 to 20% byweight based on the weight of said resole composition. The acid catalystbrings the pH of the resole composition to generally less than a pH of 3giving an exotherm to aid in blowing said foam and causing rapidmethylene bridge formation to crosslink and cure the foam. The strongacids remain in the foam and are water leachable leading to corrosionproblems.

Most basic materials if added to the resole composition reactpreferentially and rapidly with the acid catalyst reducing itseffectiveness as a catalyst. It has been found that large calcium oxideparticles will unexpectedly allow the resin composition to foam and curewith acid catalysts yet yield a cured foam having a pH of about 5 to 10.Corrosion tests showed the foam to be non-corrosive as disclosed in theExamples.

EXAMPLE 1

A base catalyzed aqueous resole resin solution is prepared by reacting1.57 mol of aqueous formaldehyde (50%) per 1 mol of phenol in thepresence of 0.035 mol of sodium hydroxide and 0.032 mol of calciumhydroxide, initially below 60° C., to control reaction exotherm. Thereaction is then conducted at 60°-70° C. range until the unreactedformaldehyde content drops below 0.5%. The reaction is cooled to 40° C.and 0.033 mol of oxalic acid is added with agitation. The resultingresin has a viscosity of 450 cps.

EXAMPLE 2

A base catalyzed resole resin solution is prepared by reacting 2.54 molof aqueous formaldehyde (50%) per 1 mol of phenol in the presence of0.035 mol of sodium hydroxide and 0.14 mol of calcium hydroxide,initially below 60° C., to control reaction exotherm. The reaction isthen conducted at 70° C., reflux until the unreacted formaldehydecontent drops to 2.3%. The reaction is cooled to 50° C., and 0.14 mol ofoxalic acid is added rapidly with agitation. The viscous dispersion(Brookfield viscosity 3800 cps) is stable to storage at 0°-10° C., withno bottom settling.

EXAMPLES 3-10

To 100 parts of resole resin of Example 2 were added 10 parts of Freon113.sup.(a) and 2 parts DC-193.sup.(b) surfactant and mixed. The UltraTX.sup.(c) acid (50% in glycerine) was mixed in rapidly and mixtureheated to 65° C. for a period of time sufficient to foam and cure thefoam. The latent acid neutralizers (calcium oxide particles) when used,were added before the acid. The following examples in Table 1 show theeffect of latent acid neutralizers of this invention upon foamformation, pH of foamed composition and corrosion of iron metal tabs informed composition.

                  TABLE 1                                                         ______________________________________                                         Ex-  Acid    CaO     CaO      Stable      Corro-                             amples                                                                              (parts) (parts) (Mesh size).sup.(g)                                                                    Foam.sup.(d)                                                                         pH.sup.(e)                                                                         sion.sup.(f)                       ______________________________________                                        3     20      6       <150     no     --   --                                 4     20      6       40-60    yes    11.0 none                               5     20      4       40-60    yes    9.2  none                               6     20      2       40-60    yes    2.9  yes                                7     20      10      40-60    yes    12.0 none                               8     20      15      40-60    yes    13.0 none                               9     20      6       > 40     yes    11.0 none                               10    20      0       --       yes    2.2  yes                                ______________________________________                                         .sup.(a) trichlortrifluorethane                                               .sup.(b) siloxaneoxyalkalene polymer                                          .sup.(c) toluenesulfonic and xylene sulfonic acid mixture                     .sup.(d) foamed to a density of about 2 lbs./per cu.ft. (PCF) having a        fine closed cell size of about 0.01 to 0.030 mm.                              .sup.(e) age foam 3 days, crush 5 gms in 100 cc. of water and test pH         .sup.(f) iron tab immersed for 24 hours in solution from test (e) and         corrosion evaluated                                                           .sup.(g) (mesh size of 40-60) through 40 mesh standard screens and            retained on 60 mesh                                                      

What is claimed is:
 1. An improved foamable resole resin compositioncurable to a non-corrosive foam, comprising, a resole resin, a blowingagent and a surfactant, wherein the improvement comprises having presentin said composition dispersed particles consisting of calcium oxide andhaving a particle size larger than 60 mesh.
 2. A composition of claim 1wherein said resole resin is contained in an aqueous solution having apH of about 3 to
 8. 3. A composition of claim 2 wherein said resolecomprises:A. a resole resin having a number average molecular weight isless than about 300, a water tolerance greater than 50%, a combinedformaldehyde to phenol ratio in the range of from about 1.0:1 to 2.9:1,and B. a dispersion of insoluble oxalate salt particles, wherein saidresole being prepared with a catalyst comprising alkaline earth metalshydroxides selected from the group consisting of magnesium, calcium,barium, strontium and mixtures thereof, said pH being adjusted with acompound selected from the group consisting of oxalic acid, ammoniumoxalate and mixtures thereof providing a stable dispersion of insolubleoxalate salt particles of said alkaline earth metal ions in saidsolution, wherein said solution is stable to salt flocculation at aresole resin content of from about 60 to 99% by weight.
 4. A compositionof claim 3 having an aqueous solution wherein said pH range is 6 to 8.5,the resole resin having an average molecular weight of from about 150 to300, a water tolerance greater than 50%, a combined formaldehyde tophenol ratio of from about 1.0:1 to 2.9:1, wherein the inert oxalatesalt is calcium or barium oxalate and wherein said resole resin ispresent in from about 60 to 99% by weight of said solution.
 5. Acomposition of claim 1 wherein said calcium oxide is present in saidcomposition in an amount of about 4 to 15% by weight of saidcomposition.
 6. A composition of claim 1 wherein said calcium oxide hasa particle size passing through a 40 mesh screen and being retained on a60 mesh screen.
 7. A composition of claim 1 wherein said blowing agentis selected from the group consisting of carbon dioxide, nitrogen,water, aliphatic hydrocarbons, fluorohydrocarbons, chlorohydrocarbons,chlorofluorohydrocarbons, air and mixtures thereof.
 8. A composition ofclaim 1 wherein said blowing agent is present in amounts of from about 1to 20% by weight based on said composition.
 9. A composition of claim 1wherein said surfactant is selected from the group consisting ofpolyethers, polyalcohols, siloxane-oxyalkalene polymers, quaternaryammonium compounds, sorbitan compounds and mixtures thereof.
 10. Acomposition of claim 1 wherein said surfactant present in amounts offrom about 0.3 to 5% by weight based on said resole resin.
 11. Animproved process for preparing a foamable resole resin composition,curable to a non-corrosive foam, comprising blending a resole resin, ablowing agent and a surfactant wherein the improvement comprisesdispersing in said composition particles consisting of calcium oxide andhaving a particle size larger than 60 mesh.
 12. A process of claim 11wherein said resole resin is contained in an aqueous solution having apH of about 3 to 8.5.
 13. A process of claim 11 wherein said resolecomprises:A. a resole resin having a number average molecular weight isless than about 300, a water tolerance greater than 50%, a combinedformaldehyde to phenol ratio in the range of from about 1.0:1 to 2.9:1,and B. a dispersion of insoluble oxalate salt particles, wherein saidresole being prepared with a catalyst comprising alkaline earth metalshydroxides selected from the group consisting of magnesium, calcium,barium, strontium and mixtures thereof, said pH being adjusted with acompound selected from the group consisting of oxalic acid, ammoniumoxalate and mixtures thereof providing a stable dispersion of insolubleoxalate salt particles of said alkaline earth metal ions in saidsolution, wherein said solution is stable to salt flocculation at aresole resin content of from about 60 to 99% by weight.
 14. A process ofclaim 11 having an aqueous solution wherein said pH range is 6 to 8.5,the resole resin having an average molecular weight of from about 150 to300, a water tolerance greater than 50%, a combined formaldehyde tophenol ratio of from about 1.0:1 to 2.9:1, wherein the inert oxalatesalt is calcium or barium oxalate and wherein said resole resin ispresent in from about 60 to 99% by weight of said solution.
 15. Aprocess of claim 11 wherein said calcium oxide is present in saidcomposition in amount of 4 to 15% by weight of said composition.
 16. Aprocess of claim 11 wherein said calcium oxide has a particle sizepassing through a 40 mesh screen and being retained on a 60 mesh screen.17. A process of claim 11 wherein said blowing agent is selected fromthe group consisting of carbon dioxide, nitrogen, water, aliphatichydrocarbons, fluorohydrocarbons, chlorohydrocarbons,chlorofluorohydrocarbons, air and mixtures thereof.
 18. An improvedprocess of claim 11 wherein said blowing agent is present in amounts offrom about 1 to 20% by weight based on said composition.
 19. A processof claim 11 wherein said surfactant is selected from the groupconsisting of polyethers, polyalcohols, siloxane-oxyalkalene polymers,quaternary ammonium compounds, sorbitan compounds and mixtures thereof.20. A process of claim 11 wherein said surfactant is present in amountsof from about 0.3 to 5% by weight based on said resole resin.
 21. Acured non-corrosive foam formed from the composition of claim 1 whereinthe foam was cured with a acid condensing agent, said cured foam havinga pH of 5 to
 10. 22. A cured non-corrosive foam formed with the processof claim 11 wherein the foam was cured with an acid condensing agent,said cured foam having a pH of 5 to
 10. 23. An improved foamable resoleresin composition curable to a non-corrosive foam, comprising, a resoleresin, a blowing agent and a surfactant, wherein the improvementcomprises having present in said composition dispersed particlesconsisting of calcium oxide and having a particle size larger than 60mesh wherein calcium oxide is present in said composition in an amountof about 4 to 15% by weight of said composition.
 24. An improvedfoamable resole resin composition curable to a non-corrosive foam,comprising, a resole resin, a blowing agent and a surfactant, whereinthe improvement comprises having present in said composition dispersedparticles consisting of calcium oxide and having a particle size passingthrough a 40 mesh screen and being retained on a 60 mesh, wherein saidcalcium oxide is present in said composition in an amount of about 4 to15% by weight of said composition.
 25. An improved foamable resole resincomposition curable to a non-corrosive foam, comprising, a resole resin,a blowing agent and a surfactant, wherein the improvement compriseshaving present in said composition dispersed particles consisting ofcalcium oxide and having a particle size passing through a 40 meshscreen and being retained on a 60 mesh, wherein said calcium oxide ispresent in said composition in an amount of about 4 to 15% by weight ofsaid composition and wherein said resole comprises:A. a resole resinhaving a number average molecular weight less than about 300, a watertolerance greater than 50%, a combined formaldehyde to phenol ratio inthe range of from about 1.0:1 to 2.0:1, and B. a dispersion of insolubleoxalate salt particles, wherein said resole being prepared with acatalyst comprising alkaline earth metals hydroxides selected from thegroup consisting of magnesium, calcium, barium, strontium and mixturesthereof, said pH being adjusted with a compound selected from the groupconsisting of oxalic acid, ammonium oxalate and mixtures thereofproviding a stable dispersion of insoluble oxalate salt particles ofsaid alkaline earth metal ions in said solution, wherein said solutionis stable to salt flocculation at a resole resin content of from about60 to 99% by weight.
 26. An improved process for preparing a foamableresole resin composition, curable to a non-corrosive foam, comprisingblending a resole resin, a blowing agent and a surfactant wherein theimprovement comprises dispersing in said composition particlesconsisting of calcium oxide and having a particle size passing through a40 mesh screen and being retained on a 60 mesh screen, said calciumoxide being present in said composition in amount of 4 to 15% by weightof said composition, said resole comprising:A. a resole resin having anumber average molecular weight less than about 300, a water tolerancegreater than 50%, a combined formaldehyde to phenol ratio in the rangeof from about 1.0:1 to 2.9:1, and B. a dispersion of insoluble oxalatesalt particles, said resole being prepared with a catalyst comprisingalkaline earth metals hydroxides selected from the group consisting ofmagnesium, calcium, barium, strontium and mixtures thereof, said pHbeing adjusted with a compound selected from the group consisting ofoxalic acid, ammonium oxalate and mixtures thereof providing a stabledispersion of insoluble oxalate salt particles of said alkaline earthmetal ions in said solution, wherein said solution is stable to saltflocculation at a resole resin content of from about 60 to 99% byweight.